Answer:
The correct answer is - it is an error in the observation.
Explanation:
Backlash error is the error in the motion that takes place during shifting the direction of gears. A backlash error is an error in the observation which occurs due to the wear and tear of threads of the screw observed that takes place at the time of reversing the direction of rotation of the thimble where the tip of the screw does not move in the opposite direction but remains stationary for a part of the rotation.
Avoid backlash error:
While taking measurements, the screw should be rotated in one direction only.
